1. Field of the Invention
This invention relates to automatically purged air compressor tanks and air lines to remove moisture, oil and other foreign material.
2. Discussion of Related Art
It is commonly known that various contaminants such as moisture, oil and rust particles build up in the tank and lines of a compressed air system. This foreign matter must be removed periodically in order to avoid damage to the system. One common method for purging a compressed air system is by use of a manual valve disposed in an outlet of the compressed air tank. However, manually operated valves do not dry the tank out and require constant attention. Accordingly, the need for a better system of draining compressed air systems has arisen.
A typical automatic drainage system uses a float connected to a valve which is opened by the float when water reaches a predetermined level. An example of this system can be seen in U.S. Pat. No. 190,895.
Another type of known drainage system is shown in U.S. Pat. No. 3,175,572. This system operates on a differential in pressure. The system works well for the removal of moisture but tends to become inoperative due to rust and other foreign material.
Other known systems use electrical timing mechanisms to energize a high pressure solenoid valve which drains the air tank. These systems suffer the disadvantage that the solenoid valve is operated only at predetermined times which are dependent upon the timer settings and not on the operating cycle of the system.
Some drainage devices are known which operate in dependance upon the operating cycle of the compressor system. U.S. Pat. No. 3,014,687 discloses an apparatus for draining a compressed air tank wherein the compressed air usually released to the atmosphere when the compressor stops is used to open a drain valve.
U.S. Pat. No. 3,341,111 discloses an automatically controlled drain valve wherein compressed air automatically opens the drainage valve at the beginning of each operating period of the compressor motor.
U.S. Pat. No. 3,646,727 shows a method and apparatus for automatically draining a liquid condensate from a tank wherein the drainage valve is opened and closed periodically by a pneumatic diaphragm.
U.S. Pat. No. 3,845,778 discloses an automatic drain valve device which is opened and closed by an abuttment that moves responsive to changes in pressure of a fluid in a storage reservoir.